// Problem: 
// Contest: 
// URL: 
// Memory Limit: 
// Time Limit: 
// #pragma GCC optimize("Ofast")
// #pragma GCC optimize("unroll-loops")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
#include<bits/stdc++.h>
using namespace std;
#define int long long
inline int read(){
	int s=0,w=1;
	char ch=getchar();
	while(ch<'0'||ch>'9'){if(ch=='-')w=-1;ch=getchar();}
	while(ch>='0'&&ch<='9') s=s*10+ch-'0',ch=getchar();
	return s*w;
}
signed main()
{
	int t=1;
//	cin>>t;
	while(t--)
	{
		string a,b,c;
		cin>>a>>b>>c;
		for(int i=0;i<4;i++)
		{
			if(a[i]==b[i])
			{
				cout<<a[i];
				continue;
			}
			if(a[i]==c[i])
			{
				cout<<a[i];
				continue;
			}
			if(c[i]==b[i])
			{
				cout<<b[i];
				continue;
			}
		}
	}
	return 0;
}
